Many types of turf mowing equipment are known. Such equipment can be classified into those mowers which include one or more rotary cutting units and those which include one or more reel cutting units. A rotary cutting unit usually includes one or more rigid steel blades rotated within a housing in horizontal cutting planes to sever grass or other vegetation at a predetermined height above the ground. Turf mowers having rotary cutting units are often referred to as rotary mowers since the blades revolve in a rotary fashion within the cutting unit.
A reel cutting unit on the other hand typically includes a frame within which is horizontally rotatably mounted a reel possessing a plurality of helical blades. The rotating reel blades pass in close proximity to a bedknife which spans the cutting unit frame parallel to the reel axis. Grass blades are sheared at the reel blade/bedknife interface.
While rotary cutting units are generally suitable for most purposes, it is generally perceived that reel units provide a higher quality, more precise cut. Since the present invention pertains to reel mowers, the remainder of this discussion will be so directed.
During use of a reel mower, it is often thought desirable to catch the grass clippings, particularly when mowing golf greens using a greensmower. Conventional wisdom is that grass clippings should be caught to protect the green from fungus growth and thatch build-up and to enhance the uniformity and speed of the green. Greens can be raked, aerated and/or verticut to eliminate thatch but it is unquestionably more economical to prevent the formation of thatch in the first instance, by not allowing clippings to accumulate on the green.
The present invention pertains to reel mower grass catchers generally. The invention will be described primarily in terms of a greensmower catcher, but those skilled in the art will recognize that the reel mower grass catcher of the present invention could be applied to reel mowers other than greensmowers.
Various types of reel mower grass catchers have been tried in the past with varying success. Certainly the simplest reel mower grass catcher is an open basket having a bottom wall, side walls and a rear wall, but being completely open at the top and front (assuming a rear mounting configuration). U.S. Pat. No. 1,484,084, issued to F. L. Rohrbach, and U.S. Pat. No. 3,875,729, issued to T. J. Partsch, are examples of this very basic type of reel mower grass catcher.
Open catchers. e.g., Rohrbach and Partsch work quite well in conjunction with mowers having low speed reels, typically manually propelled units. In fact, open baskets have traditionally been associated with walk-behind, manually-propelled, unpowered moWers, to which they are normally rear mounted The reels of such mowers, being geared to the wheels in most cases rotate at a relatively low speed and do not "pump" a large quantity of air/grass into the catcher. The grass is rather gently propelled off of the bedknife and into the catcher.
On the other hand, open catchers don't work particularly well with mowers having higher speed, typically powered reels. High speed reels, all things being equal can produce very small clippings, perhaps down to 0.03 inch long, depending on a variety of factors. Higher speed reels also pump a significant quantity of air. Thus open catchers are generally unsuitable for powered reels because the high air flows tend to carry the small clippings out of the confines of the basket.
In part because of the problems associated with open catchers described above, completely closed catchers developed. An example of this type of catcher is shown in U.S. Pat. No. 3,408 801, issued to H. E. Kroll. This type of catcher has solid front, bottom, side and top walls which combine to form something akin to a five-sided shoe box with one missing end wall (the rear wall for a front mounted catcher like that shown in Kroll) which forms a mouth for accepting the air/grass stream issuing off of the reel. Although at first glance this may seem to be an acceptable solution to the problems associated with open catchers, given the fact that the top of a closed catcher is indeed closed the primary problem with completely closed catchers is that they do not sufficiently allow for the egress of air being pumped by a high speed rotating reel. A high speed reel is in some sense like a centrifugal air pump with the spiral blades functioning like the vanes of the pump. Not only does a high speed reel cut grass and propel the clippings toward the catcher it also pumps a considerable amount of air. The only way for the pumped air to escape a completely closed catcher is back through the inlet or mouth of the catcher. This backflow interferes with the forward flow into the catcher, entrains a significant percentage of the clippings that should have ended up in the catcher and deposits them onto the surface being mowed. As noted above if clippings are allowed to accumulate on the green, fungus growth and thatch build-up may result
Also closed catchers are not configured to accommodate the angular manner in which the air/grass mixture comes off a reel. The spiral blades of a reel tend to throw the grass at a lateral angle away from the path of travel of the mower. Thus, even if a closed catcher is designed to capture most of the grass thrown laterally off of the reel, the grass which does land in the catcher tends to collect in one side and is not evenly distributed across the width of the catcher. This necessitates more frequent emptying of the catcher, and in extreme cases can actually detrimentally affect the quality of cut. Interestingly enough, the non-uniform filling problem occasioned by the spiral blades has been addressed by open catcher designs but apparently not by closed catcher designs. The Rohrbach and Partsch references, discussed above disclose, open catchers having mechanical means for taking that phenomenon into account to attempt to achieve a fairly uniform distribution of grass within the grass catcher. Rohrbach, for example, includes a catcher which is not mounted directly behind the bedknife but instead is asymmetrical with respect to the longitudinal centerline of the mower The sides of the catcher extend rearwardly at a lateral angle to the path of travel of the mower so as to be more accurately aligned in the path of travel of the severed grass clippings. Thus the operator does not have to frequently stop to manually even up the distribution of the cut grass over the bottom of the catcher. One problem with the Rohrbach approach, however, is that the increased width of the catcher makes it somewhat impractical to use along borders or fencelines. The Partsch reference teaches the use of a guide attachment mounted directly behind the bedknife. The guide attachment includes vanes which supposedly counter or intercept the lateral flow of clippings and help to arrange the clippings uniformly over the entire bottom of the grass catcher. Again, Rohrbach and Partsch disclose open catchers, and their suggested solutions to the lateral grass throwing problem discussed immediately above have not been applied, apparently, to closed catchers.
To allow the incoming air to escape from a closed catcher, while at the same time retaining the grass clippings within the catcher, attempts have been made to add screens or meshes to the otherwise solid walls of the closed grass catcher. An example of this type of grass catcher has been offered by The Toro Company assignee herein for use with the Toro Series 4 greensmower. In theory, such a screened catcher is perfectly adequate, for the air pumped into the catcher by the reel is allowed to escape through the screen, but the holes in the screen are sufficiently small to prevent the escape of grass clippings. In practice, however, such screens or meshes tend to become clogged with grass after a period of time and the catcher in effect reverts to a completely closed catcher.
Presumably because of problems associated with screened (but otherwise closed) catchers, attempts were made to make a more or less closed catcher having rather large slots or the like which would not tend to clog up but would allow air to freely escape the catcher. An example of this type of catcher is shown in U.S. Pat. No. 4,080,774 issued to R. G. Knight. In the Knight catcher, a large slot is formed between the forward edge of one wall of the catcher and the rear edge of a deflector plate attached to the mower. While this type of slotted (but otherwise closed) catcher is adequate in some conditions, e.g., heavy or wet grass, it is not particularly efficient when the grass clippings are quite small and dry due to the fact that a certain amount of the air/grass stream can jet more or less directly through the slot formed at the top of the catcher. Also, the Knight catcher appears to be symmetrical with respect to the longitudinal centerline of the mower, and therefore the grass would tend to pile up on the side of the catcher favored by the cutting reel. A simple slotted catcher like that shown in Knight would, however, be quite cost effective and simple to manufacture.
A slotted catcher which seemingly addresses some of the problems associated with the simple slotted Knight-type catcher is disclosed in U.S Pat. No. 3,521,436, issued to E. G. Venzke. The Venzke catcher could be categorized as a "slotted closed catcher" in spite of the fact that it has a rather large mouth or inlet opening. The Venzke catcher has an upwardly facing exhaust opening which supposedly allows air to escape while at the same time containing the grass clippings. The exhaust opening includes a fairly narrow throat and a diverging portion so as to, in theory, slow down the air to the point that the grass particles fall back into the catcher. The Venzke catcher also includes a screen which extends across the full width of the exhaust opening which itself extends across the whole width of the upper portion of the catcher.
Although the Venzke catcher may represent an advance over the simple slotted Knight-type catcher, in fact the Venzke-type catcher is disadvantageous in several respects. For one thing, the Venzke catcher, being rather open at its mouth and exhaust opening and lacking flow baffles, would not create a tortuous enough flow path to dissipate air flow energy sufficiently to allow grass particles to separate out. Also because of the symmetrical design of the Venzke catcher with respect to the longitudinal centerline of the catcher and the mower e.g.. the full width exhaust opening, the grass will naturally tend to pile up on the side favored by the rotating reel. That is, Venzke simply hasn't accounted for the way the grass/air stream exits the reel at an angle. And, the Venzke-type catcher includes a screen which may tend to clog under some circumstances, and, even if clogging is avoided by using rather large openings in the screen, the screen obviously contributes to greater expense and user inconvenience.
The present invention is a slotted (but otherwise closed) catcher which addresses the problems associated with prior art reel mower grass catchers. Applicants have devised a novel way to separate grass clippings from the air stream thrown off a rotating reel by reducing the kinetic energy of the air/grass stream being "pumped" by the reel. Applicants' catcher creates enough turbulence to dissipate the kinetic energy of the air/grass mixture sufficiently to allow the grass (including even the smallest and driest of grass clippings) to fall out of the air stream and into the catcher. Furthermore, Applicants' catcher is designed to force the "captured" grass clippings to uniformly cover the bottom of the basket.